Relatively low definition displays (such as commonly-used liquid crystal displays used in laptop computers, PDA and cell phone devices, and other kinds of flat panel monitors) often display text that appears to have rough and jagged edges. This may also occur when rendering text image from a low resolution source (such as a web page) using a high-resolution rendering device (such as the printer). This phenomenon is referred to as “aliasing” and occurs when an original image containing high spatial frequencies is “aliased down” by rendering on a low-frequency device.
Various font smoothing approaches have been developed to reduce the effects of aliasing. Font smoothing works by adding intermediate scaled pixels to the comers, curves and diagonals of characters in order to make them appear to be smoother and less jagged than would otherwise appear. Grayscale anti-aliasing is one approach that works by assigning pixels of intermediate values to around the edges of aliased characters, which blurs the edges of the aliased characters. The blurred edges of the aliased characters render the jagged edges to be less noticeable to the human visual system, although the clarity of the characters is often decreased.
ClearType® is another font smoothing approach that improves the readability of text runs. ClearType® works by using individual vertical color stripe elements for every pixel of an LCD screen. Thus ClearType® (using an LCD) can display features of text using horizontal fractions of a pixel. Using fractions of a pixel width increases the apparent resolution of the display such that the text is easier to read and human fatigue is lessened. (This background information is not intended to identify problems that must be addressed by the claimed subject matter.)